The southbound lanes of Interstate 5 in Sodo will undergo major repaving for the first time since they opened in 1967, a job that requires night and weekend lane reductions all summer.

The work zone stretches for 1 1/4 miles from the Interstate 90 junction to just beyond the West Seattle Bridge/Columbian Way exit. That’s an area where steel expansion-joint covers routinely loosen and clang, until maintenance workers re-tighten them.

Sometimes the steel even pops up, requiring emergency fixes to prevent a car crash. Sudden joint damage caused a 13-mile traffic jam in November 2015, and a 10-mile slowdown in May 2014.

Traffic Lab is a Seattle Times project that digs into the region’s thorny transportation issues, spotlights promising approaches to easing gridlock, and helps readers find the best ways to get around. It is funded with the help of community sponsors Madrona Venture Group and PEMCO Mutual Insurance Company. Seattle Times editors and reporters operate independently of our funders and maintain editorial control over Traffic Lab content.

The $25.7 million project includes not only a thin layer of new concrete, but also replacement of 40 expansion joints with new-generation silicone and epoxy fillings.

Overnight ramp and lane closures could run from 7 p.m. to 5 a.m., starting Monday, the Washington State Department of Transportation announced.


And then in summertime, one or more lanes will be closed all weekend between 7 p.m. Fridays and 5 a.m. Mondays. Specific dates aren’t scheduled yet but that phase could begin by mid-June.

The state will avoid blocking lanes during holiday weekends and sports events when more people drive. A total 16 weekend-long lane reductions, including one full southbound I-5 closure, are expected in 2021 and 2022.

Elevated roadway decks and expansion joints there were noticeably wearing out by the late 2000s. WSDOT did repair the northbound side, during an epic project in August 2007, but the state Legislature and agency managers placed other budget priorities ahead of fixing the southbound side.

WSDOT performed significant repaving to segments of I-5 from 2017 to 2019 around Federal Way, Tukwila and Seattle, and this summer’s Sodo work is the next step in an ongoing “Revive I-5” program.

Highway and bridge preservation have long gone underfunded, but the Legislature and Gov. Jay Inslee this year doubled that spending to $849 million for 2021-23, still short of WSDOT’s stated need.

About 45 miles to the north, WSDOT is warning drivers that its southbound I-5 Stillaguamish River Bridge, built in 1933 near Arlington, will close in June for five months for repainting. Southbound traffic will be detoured across the median to share the northbound bridge, at a 50 mph speed limit.

Traffic updates are posted on the state’s Seattle area construction webpage and the @WSDOT_traffic Twitter feed.